Bells palsy is due to reactivation of herpes simplex virus till now.
Palsy cannot be or rather should not be cuz of stress. Ideally he needs to get a consult with treatment in form of steroids, antivirals and protection for eye as it remains open.
Later physiotherapy is needed.
Next Steps
avoid getting cold and letting the eye dry.
Health Tips
keep eyes moist
avoid listening to songs loudly
consult a ENT specialist